In recent years, the optical disk drives mounted in DVD (Digital Versatile Disk) recorders, and the hard-disk drives (HDDs) mounted in products such as personal computers and DVD recorders have been required to be able to transfer larger volumes of information at higher speeds in response to the variegation and diversification of information. These electronic apparatuses also tend to contain a plurality of disk drives in order to improve performance. Meanwhile, the electronic apparatuses in which optical disk drives and an HDD are to be mounted are desired to be downsized in response to the diversification of uses.
In disk drives, a spindle motor for driving a recording medium rotates at high speed to meet the above needs associated with the electronic apparatuses. The high-speed rotation, however, increases not only the heat stemming from the stator coil of the spindle motor, but also the amount of frictional heat occurring on the rotating shaft and bearings of the motor. In addition, the high-speed rotation further increases the noise arising from the disk rotation itself, and seek-associated noise. The increases in the amount of heat and in noise level reduce the performance of the disk drive. In addition, they are becoming a problem in terms of ambient environment.
In order to solve these problems, there are known techniques that allow heat to be released from a disk drive by ensuring an escape route for the heat to the outside of the disk drive while at the same time suppressing noise leakage to the disk drive exterior by maintaining airtightness of the drive under a mounted state thereof.
For example, JP-A-2006-127718 describes a technique that makes it possible, by insulating a disk drive with a vibration- and sound-absorbent, porous, and elastic member having heat-releasing holes formed therein, to release the heat that the disk drive has generated, from the heat-releasing holes formed in the porous elastic member.
Also, JP-A-2004-234777 describes a technique that allows noise from a hard-disk drive to be absorbed, and leakage of the noise to outside to be suppressed, by disposing a sound-absorbing material in a disk casing, installing the hard-disk drive in suspended form at the covering member of the disk casing, and forming an airtight space in the casing.
In addition, JP-A-2005-285154 describes a technique in which a disk casing is grooved on the outer surface thereof to increase a contact area with respect to outside air and thus to improve a heat-releasing effect.
Furthermore, in the technique described in JP-A-2005-222585, the seek noise level of a disk drive is reduced by including the disk drive in an outer enclosure with a foaming resin sheet attached thereto, and internally stored heat is released from the outer enclosure through an infrared-ray exchanging member heat-connected between the outer enclosure and the enclosure of the drive so as to be disposed to both enclosures.
Moreover, JP-A-2004-326906 describes bringing a disk drive into contact with the support unit of a heat-conductive plastic material to release heat from the disk drive through the heat-conductive plastic material.
The above conventional techniques, however, have the respective problems to be solved. For the technique described in JP-A-2006-127718, the number of heat-releasing holes lies in the relationship of the following trade-off: it is preferable that this number be larger for releasing a larger deal of heat, whereas it is preferable that the number be smaller for noise suppression.
For the technique described in JP-A-2004-234777, there is the problem that if the amount of heat generated by the hard-disk drive exceeds the amount of heat released from the covering member, increases in the temperature of the hard-disk drive cannot be sufficiently suppressed.
For the techniques described in JP-A-2005-285154 and JP-A-2005-222585, since the hard-disk drive is constructed to release heat through the external wall of the enclosure including the hard-disk drive, the amount of heat released depends on the surface area of the external wall and thus a problem occurs that is similar to that of the technique described in JP-A-2004-234777.
For the technique described in JP-A-2004-326906, since the support unit for releasing heat is constructed to include the entire hard-disk drive, it is unknown whether this heat-releasing construction is optimal for a case in which the internal heat-generating section of the hard-disk drive partly exists, or for a case in which a plurality of heat-generating sections are present.